Efficient pressure-transformer for fluids

Fluid transformer utilizes fluid under pressure at one level to drive series of free pistons in positive displacement pump. Pump in turn delivers hydraulic fluid at different pressure level to a load. Transformer is constructed of corrosion resistant materials and is extremely light and compact in relation to capacity

Charter School Replication: Growing a Quality Charter School Sector

NACSA's Policy Guide series is intended to support state legislatures and charter school advocates in creating policy environments that result in high quality authorizing and high quality schools. This guide outlines key considerations for policymakers committed to supporting the replication of existing successful charter school models

Two-Dimensional Vortex Sheets for the Nonisentropic Euler Equations: Nonlinear Stability

We show the short-time existence and nonlinear stability of vortex sheets for the nonisentropic compressible Euler equations in two spatial dimensions, based on the weakly linear stability result of Morando--Trebeschi (2008) [20]. The missing normal derivatives are compensated through the equations of the linearized vorticity and entropy when deriving higher-order energy estimates. The proof of the resolution for this nonlinear problem follows from certain \emph{a priori} tame estimates on the effective linear problem {in the usual Sobolev spaces} and a suitable Nash--Moser iteration scheme.Comment: to appear in: J. Differential Equations 2018. arXiv admin note: substantial text overlap with arXiv:1707.0267